Simplistic NJFET RIAA - Page 1233 - diyAudio
Go Back   Home > Forums > Source & Line > Analogue Source

Analogue Source Turntables, Tonearms, Cartridges, Phono Stages, Tuners, Tape Recorders, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th March 2014, 05:57 PM   #12321
Turbon is offline Turbon  Sweden
diyAudio Member
 
Turbon's Avatar
 
Join Date: Aug 2011
Location: South
Rick.

I had to get temp down since my simplistic is constantly on living in a bookshelf behind CD's. Before the mesh it was constantly +15C above ambient and with mesh +7C.
So you better find a scheme that fits your setup.

Interesting to get a report abt your caps.

Regards
__________________
These are my principles, and if you don't like them... well, I have others.
  Reply With Quote
Old 19th March 2014, 07:35 PM   #12322
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Default Dubious 2SK117GR

Check your 2SK117GR stash if you recently bought any. I have caught a circulating specimen that presents wrong curves (not flat but diagonal). It invariably has GR OK batch number printed on it. Its IDSS, Yfs, Vgs may appear in range and it will work (maybe will bias lower under small VDS) but surely it will not perform OK dynamically.

In general, proper 2SK117GR should have "one" digits printed like vertical featureless lines, should show a short prominent ridge along the center front when viewed from top, show a bit of copper color when viewed from the back where the pins enter the plastic. Much like 2SK170BL.

I alerted tea-bag about it and he investigated his stash. He found a number but he received those very recently and he could have sent out only about 80 pcs most likely in BIB 1.1 bags not in FSP bags. If you spot those bad apples let him know via PM. Do check the new FSP mini-kit arrivals nonetheless or whatever 117s you bought yourself from vendors especially recently.
  Reply With Quote
Old 19th March 2014, 09:21 PM   #12323
diyAudio Member
 
Join Date: Jun 2006
Default My turntable and cartridge

Dear SALAS,

I think my table is good.

An amalgamation of parts with years of evolution.

Starting with a 50hz LENCO L75 all that remains is the motor, idler arm, and the bearing spindle.

A REINDERS top plate atop an OSWALDS MILL oversized slate plinth - there is area behind enough to place the phono stage to minimize distance from the cartridge to the input. I use a single length of CARDAS tonearm wire from the cartridge to the phono amp. AS short as possible.

The bearing is a MIRKO titanium bearing. I also have his titanium idler wheel.

The platter has two big O rings around it (inspired by ORACLE) and atop that are 5 of TTWEIGHTS copper mats - the top one having the carbon fiber mat on top. Plenty of mass and the layers add damping. A TTWEIGHTS record weight finishes off the load I put on the bearing's thrust plate. A length of wooden dowel is needed for a spindle because of the height of the platter mats.

The motor has had a ceramic ball bearing installed where the nose screw is (I think I am remembering the name correctly, if not LENCO folks will know what I mean). There is also a copper plate epoxied to the bottom of the motor for added mass and added stiffness of the motor frame. Suspension springs adjusted accordingly.

A PS AUDIO P300 gives me the 50 hz AC.

The tonearm is an EMINENT TECHNOLOGY that has a longer than stock length carbon fiber arm (to clear the TTWEIGHTS peripheral platter weight). The arm uses what Mr. Thigpen calls the low pressure high volume manifold which requires a full size air compressor (outside of the house). The arm has been stripped of its mounting hardware which struck me as too loose. The manifold, once the correct height is found, is clamped to the plinth with a piece of ebony under the manifold and above for the clamping. A very large bronze bolt and nut are used for applying pressure.

There is a trough of silicone fluid for damping the tone arm. The paddle is attached to the back of the tone arm. Instead of the short stick for the counterweight which requires a heavy weight to do its job I am using a length of balsa, the same length as the tone arm with a small brass weight for setting tracking force. The weight itself rides slightly below the surface of the LP. This greatly reduces the moving mass of the arm.

The cartridge is a TRANSFIGURATION Temper Supreme that I have used for fifteen years. I sent it to EXPERT STYLUS a couple of years ago feeling sure it was near needing a new stylus and was told the stylus was in excellent condition. Yes, I hope that is taken as a complete and utter endorsement of the excellence and decency of EXPERT STYLUS. I would never send a cartridge to anyone else. So I continue to enjoy this cartridge. I have a back up of a ZU DENON 103 which I listened to while the TTS was on its London adventure. It was OK. When the TTS was returned to duty my ears were very grateful. Maybe I got lucky and got a really good one but I love this cartridge. I could not afford to purchase a replacement of the same quality.

I will get it rebuilt by EXPERT when the time comes.

I use a polarity switch (TUBECAD) at the phono stage with the load resistor on the output side (otherwise you get a big pop). I cannot emphasize enough the importance of listening for the best position. In my system, on most records, there is an obvious best setting. The best setting results in the most spacious sound - the stage extending further out from the speakers.

The table itself sits upon four springs and then on my first LENCO plinth, made Nantais style with alternating pieces of MDF and Baltic birch plywood (probably weighs 150 pounds) then two large spruce beams which allows space for the subwoofer crossover and the PS Audio P300 and then a large "sandbox". The springs are augmented by three stabilizing bits of wood with two having sorbothane squares. Most of the weight is taken by the springs but enough is on the sorbothane for it to work. These bits of wood make levelling the table much simpler. Even though the table is on a suspended floor one has to try very hard to upset the table while a record is playing. I think it is highly isolated from the earth.

Antiskate force is adjusted by the front to back angle of the table's deck. The only way to do this with the ET and it works just fine.

There it is, more than anyone wanted to know!
__________________
Rick McInnis
  Reply With Quote
Old 19th March 2014, 10:20 PM   #12324
Turbon is offline Turbon  Sweden
diyAudio Member
 
Turbon's Avatar
 
Join Date: Aug 2011
Location: South
, most interesting Rick. Makes me want to get mine finished...

Regards
__________________
These are my principles, and if you don't like them... well, I have others.
  Reply With Quote
Old 19th March 2014, 11:04 PM   #12325
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
After all those elaborate and costly efforts on his TT and cart I can see why Rick is investing in expensive parts for his FSP too. Good luck then Rick and let us know what you have achieved. Time is soon.
  Reply With Quote
Old 20th March 2014, 09:39 PM   #12326
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by pellesmil View Post
Ok

better now,
I guess the record i played yesterday is prob. not the best production the word has seen,
After some records tonight the sound of the riia itself is less dominant and the sound of the record is what i hear.
On Bruce Springsteen Tunnel of Love, One step up it plays bass with very good detail, better than i heard before,

Fun

Have records, will play
I chanced on Tunnel of Love and Darkness on the Edge of Town on one of my shelves today so I thought I could listen to One Step Up's bass line you mentioned. No bump up, very spectral with the PTG/II too. What I gathered by experimenting a little is that those new gen AT-33s are sensitive down to 0.1gr VTF differences regarding bass balance. I think you mentioned you have the 33EV set at 2.2gr? If you got a trusty digital scale try to decrease by 0.1gr steps down to 2gr. After you visually know the turn range on the counterweight between 2-2.2 you can slowly move finer than 0.1gr even. There is a point where the bass phrases up and all images they just open up wide and deep. Mine when set heavy sits the image height down noticeably. When correct its like there are no speakers in the room. With your biggish bass reflex speakers it may drag the bass guitar on some not so well mixed recordings if bit heavily set I think. Two Faces song from the same record just before Brilliant Disguise on same side is very good to judge if the 3D presence can gain up. Also after it got kinda broken in by now, 200R load is no problem still sweet but bit more light, its just a matter of synergy with the rest of gear choosing 150R or 200R. When new out of the box, on 200R it could had been a little harsh on some classical records when the brass instruments went loud and high. Not anymore. Alright, that was my report, maybe it can be of help since we got almost the same cart and RIAA preamp.

P.S. I did those things with neutral VTA. (i.e. the arm tube was parallel to the record's surface).
  Reply With Quote
Old 22nd March 2014, 06:18 PM   #12327
diyAudio Member
 
Join Date: Mar 2007
Hi

I have the boards and the components from Tea Bag, but I have some questions.

The 2SK117's have a large spread of Idss from 2.78mA to 5.59mA, I don't have six in the 3-4mA range, it looks like I might need to use three in the 3-4mA and three in the 4-6mA ranges between the two boards, would this be OK?

I'm confused about the values of R2 & R3 in the phono stage. I will populate both Q1 and Q2, but what values to use for R2 & R3? It's not really clear in the notes.

Thanks for the help.
  Reply With Quote
Old 22nd March 2014, 07:00 PM   #12328
RCruz is offline RCruz  Switzerland
diyAudio Member
 
RCruz's Avatar
 
Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Finally got the parts (and the time) to start building the folded using Salas boards....

Been reading the excellent pdf and my first doubt comes from the grounding arrangement.

Pic1 indicates we should connect both psu (shunt) grounds to the case/arm ground fixing....
Pic2 indicates we should use a 1r resistor to connect both psu negatives to the "safety earth arrangement"

I believe we are running into a ground loop here... is it possible ? Or the 1r resistor eliminate that problem ?
__________________
RC
  Reply With Quote
Old 22nd March 2014, 07:09 PM   #12329
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
Quote:
Originally Posted by Deco-Doctor View Post
Hi

I have the boards and the components from Tea Bag, but I have some questions.

The 2SK117's have a large spread of Idss from 2.78mA to 5.59mA, I don't have six in the 3-4mA range, it looks like I might need to use three in the 3-4mA and three in the 4-6mA ranges between the two boards, would this be OK?

I'm confused about the values of R2 & R3 in the phono stage. I will populate both Q1 and Q2, but what values to use for R2 & R3? It's not really clear in the notes.

Thanks for the help.
When you haven't got preferable IDSS 2SK117GR for all places it does not mean that you can't use different IDSS if you will understand their functions:

1. Q7 lights up the phono's input section LEDs. Anything 2.6-6.5mA will give them sufficient current. Just keep those Q7 relatively close IDSS between channels. The drop across R15 is calculated for 4-5mA and about 15V drop. You may recalculate R15 for other IDSS at hand although not critical.

2. Q3x IDSS can be any as long as you will calculate there can be enough current for driving VR2x and R3x sufficiently to develop a useful ceiling of about 36V for your ease of adjusting Rail+. The formula should be Rail=((IDSSQ3x*0.8)*(R3x+VR2x))+(0.6+1.85). i.e. The practical way is to alter the R3 value according to your IDSS at hand.

3. Q2x & Q5x have no direct voltage parameter to affect, just local bias thus dissipation in the TO-92s. Better be moderate IDSS and close together enough between channels. If having low and high to choose from, better choose low.
  Reply With Quote
Old 22nd March 2014, 07:11 PM   #12330
Salas is offline Salas  Greece
diyAudio Chief Moderator
 
Salas's Avatar
 
Join Date: Oct 2002
Location: Athens-Greece
P.S.

4. R2 R3 choice is analyzed in the guide's notes section on first paragraph. If you know your Q1-Q2 IDSS, there is a chart to choose R2 & R3 from.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



New To Site? Need Help?

All times are GMT. The time now is 09:21 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2